ISOless sensors, read noise and photography - many questions!

Started Oct 3, 2013 | Discussions
EinsteinsGhost
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Re: in one sense, pointless to use ISO above 800 on Nex C3
In reply to RussellInCincinnati, Oct 4, 2013

RussellInCincinnati wrote:

OK Alan, have put the time in studying the sensorgen site. IF you don't get color casts/banding during your raw post-processing brightening, it appears that there is no point in ever manually setting a Nex C3 to above ISO 800. Because if you do, you are just amplifying "the noise" as much as the brightness and not really getting anything that you couldn't get in post-processing with a lot more finesse and options. Will be checking this out, the practicality of staying at ISO 800, at least with Lightroom 4.4 for Windows if not RawTherapee and LightZone (i.e. latest dcRaw).

Said another way, you might as well brighten a C3 raw digitally, at your leisure if there's not enough light for ISO 800. Just let the raw file "look superficially dark" and figure you'll brighten it in post-processing.

Of course one downside of not setting ISOs above 800, just underexposing, is that you don't get a nice review of the image in-camera, it will always look grim in the playback menu.

I would normally use the post adjustment within limits, 2 stops at the most. If noise is an issue, the idea should be to expose (even slightly) to the right at any ISO. The benefit with shooting at a fixed, low ISO, as opposed to higher ISO is primarily to utilize dynamic range. Per sensorgen, the read noise on NEX-C3, for example, is at its lowest at ISO 12,800 (practically the same at 800) but 12,800 won't get the results that 800 would. Conversely, I won't be surprised if you used ISO 800 and pushed 4-stop during RAW conversion, that you will notice banding and color issues.

I rarely see situations where meaningful images require ISO 6400, that I would set ISO 800 and push 3-stops later. But, I do see 1600 and rarely, 3200, as needed. In those cases, ISO 800 and 1-2 stop push suffices. Here is a result from a trial run a while ago (NEX-3, LA-EA2, Minolta 200mm f/2.8G):

f/2.8, 1/640s, ISO 800 (+1-stop during RAW conversion)

Typically, NBA games require ISO 1600-2000 for 1/500s or faster shutter speeds with f/2.8.

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gollywop
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Re: ISOless sensors, read noise and photography - many questions!
In reply to boardsy, Oct 4, 2013

boardsy wrote:

bobn2 wrote:

boardsy wrote:

Accepting the standard definition of exposure as the amount of light registered by the sensor per unit area, and dependent solely on aperture size and shutter speed (not on ISO selection, even if this is used to influence aperture size and shutter speed!), a few questions arise in my mind:

- in order to maximise exposure and DR and minimise noise, do you really need to know your sensor's read noise and ISO DR curves?

Bobn tells us here that the flat read noise characteristic of the Nikon D7000 makes it effectively ISOless:

- if the sensor is effectively ISOless then is base ISO always optimal (providing that you can see enough of the image on your camera to compose and focus in a sub-optimal exposure scenario), or are you as well off raising it in camera (providing highlights are preserved) rather than in RAW/pp?

There are other factors to take into account, in no particular order:

- on those graphs the 'base ISO' is not always too accurate, because the sensor may have been run into non-linearity.

- there are qualitative factors as well as the measure of read noise to take into account.

Sorry, this is all a bit opaque to me - what is the upshot for practical purposes?

- is it possible or likely that the camera's ISO implementation is better tuned to its sensor and RAW data than your RAW software? Aside from highlight preservation on exposure, are there other benefits to "doing ISO" in post?

It's possible. Nikon, for instance, does some subtle gain adjustments with its cameras. Presumably they wouldn't be doing them unless the engineers thought that they brought some advantage. BTW, I think it's worthwhile distinguishing between 'processing' and 'post processing'. I think the brightness setting is best done in processing (raw conversion), not post-processing.

Do you mean: processing means RAW software (ACR, LR etc), and post-processing applies to JPG (PS, GIMP etc)?

- for a given sensor may it be more effective to raise ISO to some minimum/optimal level vis-a-vis its read noise?

Yes, I think that's true. The D7000 above is better at 200 for instance.

But it has less DR & Sat Cap and equal read noise at 200 vs 100?

- how do us non-scientists interpret these sensor graphs? E.g. for the Sony NEX C3 (probably the same sensor as my F3, maybe, lol), read noise actually drops down to ISO800 ...but so does DR! Is ISO400 the best compromise here, or should best DR (at ISO200) trump lower read noise (at ISO800)? And could this non-base ISO be valid for all shooting, or just low-light where optimal exposure becomes problematic?

DR trumps lower read noise if you need it, which is one of those judgements based on experience. A rule of thumb which covers most cameras pretty well is go with ISO but stop about 2 stops faster than base (3 for an APS-C Canon, 4 for a FF one).

You mean raise ISO in-camera as required, up to 2 (APS-C), 3 (APS-C Canon), or 4 (FF) stops?

From http://www.sensorgen.info/SonyNEX-C3.html

Alan, where you set your "normal" ISO, and when you change it when using ISO-variant (or partially-ISO-variant) shooting, depend very much on your normal shooting conditions.

A good deal of my shooting, for example, tends to be outdoors in decent light with scenes that have a DR that readily pushes my E-M5 to its limits at base ISO.  Thus, I fix ISO at base 200.  I then set exposure to ETTR (which term, by the way, applies only to shooting at base ISO).

Likewise, when shooting indoor scenes with windows whose content-detail I am desirous of keeping, the scene DR far exceeds what can be recorded so as to produce a normal looking image.  Again I use base ISO and shoot ETTR to preserve the highlights.  This results in a very dark image and entails significant boosting of the shadows and midranges during processing, while compressing highlights to retain the window details -- a process known as exposure compression.  If you're using ACR, this is accomplished by bringing up the Exposure slider to achieve desired mid-tones, dropping Highlights (possibly quite significantly, even down to -100) to retain window detail, and boosting Shadows to bring up the dark areas to an acceptable and tolerable level.

So I'm usually shooting at base ISO.  When, however, shooting conditions do not allow me to ETTR, I set aperture and SS as needed to achieve a maximum exposure value and then dial in ISO as needed up to my partial-ISO-invariant limit.  In the case of my E-M5, that's ISO 800, and that looks to be the same for your C3.  If further brightening is required, I shoot dark and apply it in processing.  When applying ISO in this way, I tend to be conservative, not always brightening in-camera to the extent that would appear to be allowed. I would rather prevent any unwarranted highlight clipping in-camera and control the brightening during processing.

If your normal shooting conditions allow achieving an adequate DR at an ISO above base (and at or below the partial-ISO-invariant limit - 800 in your case), then it makes sense to set that as your usual ISO and vary it only as required for changing scene DR conditions, lower, for example, if you need more highlight headroom.  With a partially-ISO-invariant camera, you would want to use the lowest ISO (at or below the limit) that provides you with the necessary DR. And, as Bob notes, this is not always base ISO.

Processing by the way really applies to the basic operations that convert a raw file into an image, namely application of WB, demosaicing, and fundamental tonal transformations.  Some processors accomplish more operations at this stage some less. But when people talk about applying brightening during processing, they really mean setting WB and the brightening you do with the so-called exposure slider and its associates in ACR.

ACR also accomplishes some operations, like saturation, clarity, sharpening, HSL, lens corrections, that could be considered post-processing.  The one thing that is for sure, once you've rendered your raw file into a jpeg or TIFF and sent it on to an image processor like PS, anything that is done there is post-processing.

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gollywop
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Re: ISOless sensors, read noise and photography - many questions!
In reply to rubank, Oct 4, 2013

rubank wrote:

bobn2 wrote:

I think personal tests to one's own requirements are always the best -

I hardly beleive my eyes

Only because they apparently didn't lead you to understand what's come before.  There is nothing new here.

There is a difference, by the way, between trial and error and the process of science known as the hypethetico-deductive method.  The former can be done (but, of course, need not be done) with complete blind stupidity with fortuitous outcomes.  The latter makes use of an interplay of experiment and theory, where each leads and modifies the other in a rational manner.  A theoretical understanding (model) suggests tests and predicts outcomes, experiments verify or invalidate those tests and lead to refinements of the theory.

You appear to advocate the former, Bob the latter.  But there is nothing surprising -- or, at least, there shouldn't be.

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bobn2
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Re: ISOless sensors, read noise and photography - many questions!
In reply to boardsy, Oct 4, 2013

boardsy wrote:

bobn2 wrote:

boardsy wrote:

bobn2 wrote:

Yes, I think that's true. The D7000 above is better at 200 for instance.

But it has less DR & Sat Cap and equal read noise at 200 vs 100?

Sur, but saturation capacity and DR are only of interest if you're going to use them. If your scene and chosen exposure doesn't include anything that will blow out at 200, then 200 is as good as 100, and maybe a bit better in some cases.

A bit better how, in what cases - you're getting lower DR and equal read noise at 200?

Well, the case that you're not using the extra DR, in which case it's loss is not a loss and where the quality of the noise, rather than just the amount, makes a difference. Quite often, for instance with the D7000, the noise just looks nicer at 200.

- how do us non-scientists interpret these sensor graphs? E.g. for the Sony NEX C3 (probably the same sensor as my F3, maybe, lol), read noise actually drops down to ISO800 ...but so does DR! Is ISO400 the best compromise here, or should best DR (at ISO200) trump lower read noise (at ISO800)? And could this non-base ISO be valid for all shooting, or just low-light where optimal exposure becomes problematic?

DR trumps lower read noise if you need it, which is one of those judgements based on experience. A rule of thumb which covers most cameras pretty well is go with ISO but stop about 2 stops faster than base (3 for an APS-C Canon, 4 for a FF one).

You mean raise ISO in-camera as required, up to 2 (APS-C), 3 (APS-C Canon), or 4 (FF) stops?

the 4 stops for FF was Canon only. Yes, essentially use that as your fixed working ISO, lowere it if you need more highlight headroom.

You mean not just as required by low light, to choose lowest read noise despite lower DR? Interesting, I wouldn't have expected that - so DR would only trump read noise in high DR scenes e.g. midday sun & dark shadows?

Exactly, if you aren't using the DR, it doesn't give you any advantage. When you do need it (which is actually typical with low light scenes, because they often have light sources included in the scene, which are very much brighter than a reflective 'white' at the ambient illumination.

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RussellInCincinnati
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no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to boardsy, Oct 4, 2013

Alan, am so glad you raised this thread. As a raw file user, am never going to set the Nex C3 above ISO 800 again. Because as you found also, can verify that just brightening the "underexposed" (say "ISO 3200") image in, for example, Lightroom 4.4, completely eliminates the need for bracketing exposures in the field. Amazing and embarassing to not have noticed this years ago.

Thanks also to DPreview for the Photo Science and Technology forum, and the sensorgen website. A great practical benefit after only a couple of days of perusing the forum, and noticing that setting a Nex C3 above ISO 800 cuts dynamic range as much as it raises brightness (i.e. is potentially pointless).

If had a Nex 7, would probably never set the ISO above 100. Because you don't "get anything for it" in terms of lower-light noise advantage.

It's true that the playback of "underexposed" images is not so nice in-camera, but decades of film photography, and awareness that have never sold a digital photo that didn't need some post-processing, makes me not miss that delicacy. And as you pointed out, heck you can take a moment to set your ISO high and take a test shot, if you're so anxious to see a somewhat-closer-to-final version of your photo, in-camera.

Details

When "pushing" underexposed Nex C3 raw files taken with camera set to ISO 800, can see no significant (i.e. noticeable) difference in anything one might think of to call "image quality". If there are banding or shadow etc color tint challenges to "pushing" the exposure in Lightroom 4.4, well Lightroom apparently knows how to deal with them. Put another way, in the Nex C3 case, Lightroom seems to know enough to do as good a job as Sony in amplifying the ISO 800 raw-data brightness of dark images (at least to ISO 3200 which I never go over).

ISO 3200 photo:

ISO 800 photo, "exposure" slider simply set to +1.75 EV (exposure values, F-stops) in Lightroom:

With results this similar, why would a raw user ever take bracketing exposures because of a worry about highlight detail, or bother setting a Nex C3 beyond ISO 800?

Exposure bracketing when you're above ISO 800 is clearly an antiquated artifact of the film era, if you're using raw files on a Nex C3. Instead of clogging up your camera with "bracketing in the field" images, you just have the luxury to play with the "exposure" slider (in say, Lightroom 4.4) until you get the overall brightness you want from some "underexposed" raw file. What an embarassment, looking at all the unneeded bracketing exposures in my image database.

Obviously all this is a time/error-saver for raw users of a Nex C3 taking real photos in the field. Where they otherwise would have fiddled with their cam to get it over ISO 800, or waited while their camera clattered through bracketed exposures, or been held up from taking their next exposure, while waiting for all the unnecessary raw files to shuffle on out to the memory card.

And what a delight to know that, without bothering with bracketing, you have always preserved highlight detail, in case you want the HDR look from a single exposure:

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bobn2
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Re: ISOless sensors, read noise and photography - many questions!
In reply to rubank, Oct 4, 2013

rubank wrote:

bobn2 wrote:

I think personal tests to one's own requirements are always the best -

I hardly beleive my eyes

Well, my observation would be that your eyes are unreliable.

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Reilly Diefenbach
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to RussellInCincinnati, Oct 4, 2013

Two stops is fine, four or five isn't.

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EinsteinsGhost
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to RussellInCincinnati, Oct 4, 2013

For most part, yes. Actually, the C3 did a pretty good job at ISO 3200 for that particular image. I do note a slight change in color between ISO 3200 and ISO 800+push, visible in the lower left corner (carpet). The color looks a bit washed out in the latter. And if the rendering is closer in the first, then this case may be a good example where leaving ISO 3200 might be better whereas if dynamic range becomes an issue, using lower ISO + push.

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RussellInCincinnati
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yes, stop at ISO 800 on Nex C3
In reply to gollywop, Oct 4, 2013

Gollywop: So I'm usually shooting at base ISO. When, however, shooting conditions do not allow me to ETTR [expose to the right, i.e. as much exposure as needed to get brightest parts of a scene recorded at 100% brightness], I set aperture and SS [shutter speed] as needed to achieve a maximum exposure value and then dial in ISO as needed up to my partial-ISO-invariant limit. In the case of my [Olympus] E-M5, that's ISO 800, and that looks to be the same for your C3. If further brightening is required, I shoot dark and apply it in processing.

Yes, all makes perfect sense now.

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gollywop
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Re: ISOless sensors, read noise and photography - many questions!
In reply to bobn2, Oct 4, 2013

bobn2 wrote:

rubank wrote:

bobn2 wrote:

I think personal tests to one's own requirements are always the best -

I hardly beleive my eyes

Well, my observation would be that your eyes are unreliable.

That's, of course, one of the weaknesses and drawbacks of trial and error.

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Iliah Borg
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A closer look
In reply to bobn2, Oct 4, 2013


All the conversion settings are the same except for the white balance that is sampled in the marked area on the Neutral 8 patch of CC24. Indicated Lab readings below the histogram and to the left are for that area. It seems the light changed between the shots. It is easy to see noise is quite different. That is why I asked for the raw files from a more controlled experiment.

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RussellInCincinnati
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example of convenient 4-stop "push" acceptable to many
In reply to Reilly Diefenbach, Oct 4, 2013

Einstein's Ghost: Conversely, I won't be surprised if you used ISO 800 and pushed 4-stop during RAW conversion, that you will notice banding and color issues.

Reilly Diefenbach: Two stops is fine, four or five isn't.

Reilly, in the digital era, why bother expressing an opinion without an example? For example, I find a "four stop push" from ISO 800 to 12800, Nex C3 raw files acceptable. I particularly see not the slightest hint of banding. Yes, there is greenish tint and false colors sneaking into the shadows at ISO 12800, and it seems like the noise is a touch higher, but would rather deal with that, using Lightroom 4.4 etc post-processing sliders. Instead of "unncessary" fiddling with ISO controls in the field, do "unnecessary" bracketing exposures because of worry about highlight detail, and create "unnecessary" files. "Unnecessary" relating to whether or not the upper example here is noticeably better than the lower one to the average viewer.

Above, ISO 12800 Nex C3 raw file.

Above, ISO 800, with exposure slider set to +3.91 EV in Lightroom and shadow slider set to +22. What client is going to notice the (rather correctable) green tint in shadows here, unless there was a side-by-side comparison that no regular person ever does?

My takeaway is to not bother setting ISOs above 800 on a Nex C3 for a raw workflow, with Lightroom 4.4 or other adequate raw processing software.

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boardsy
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but is your ISO3200 as good as ISO800? :-)
In reply to RussellInCincinnati, Oct 4, 2013

RussellInCincinnati wrote:

Alan, am so glad you raised this thread.

Thanks - though I was merely piggy-backing on the back of a few feverish "Is ISO part of exposure?" (- "no!") thread-wars!

As a raw file user, am never going to set the Nex C3 above ISO 800 again. Because as you found also, can verify that just brightening the "underexposed" (say "ISO 3200") image in, for example, Lightroom 4.4, completely eliminates the need for bracketing exposures in the field. Amazing and embarassing to not have noticed this years ago.

It's not obvious (or embarrassing not to have known) that many (most?) high ISO values in many (most?) cameras are not a useful sensor sensitivity gain, but simply a tag in a RAW file to tell the JPG or RAW software where to set brightness, and stretching the actual exposure (aperture & shutter speed) over the available brightness levels, so "high ISO noise" is in fact low exposure noise, exposed (!) by raising brightness levels!! I've only just discovered all this, in a personal Copernican ISO revolution!

Thanks also to DPreview for the Photo Science and Technology forum, and the sensorgen website. A great practical benefit after only a couple of days of perusing the forum, and noticing that setting a Nex C3 above ISO 800 cuts dynamic range as much as it raises brightness (i.e. is potentially pointless).

If had a Nex 7, would probably never set the ISO above 100. Because you don't "get anything for it" in terms of lower-light noise advantage.

It's true that the playback of "underexposed" images is not so nice in-camera, but decades of film photography, and awareness that have never sold a digital photo that didn't need some post-processing, makes me not miss that delicacy. And as you pointed out, heck you can take a moment to set your ISO high and take a test shot, if you're so anxious to see a somewhat-closer-to-final version of your photo, in-camera.

Details

When "pushing" underexposed Nex C3 raw files taken with camera set to ISO 800, can see no significant (i.e. noticeable) difference in anything one might think of to call "image quality". If there are banding or shadow etc color tint challenges to "pushing" the exposure in Lightroom 4.4, well Lightroom apparently knows how to deal with them. Put another way, in the Nex C3 case, Lightroom seems to know enough to do as good a job as Sony in amplifying the ISO 800 raw-data brightness of dark images (at least to ISO 3200 which I never go over).

ISO 3200 photo:

ISO 800 photo, "exposure" slider simply set to +1.75 EV (exposure values, F-stops) in Lightroom:

With results this similar, why would a raw user ever take bracketing exposures because of a worry about highlight detail, or bother setting a Nex C3 beyond ISO 800?

Exposure bracketing when you're above ISO 800 is clearly an antiquated artifact of the film era, if you're using raw files on a Nex C3. Instead of clogging up your camera with "bracketing in the field" images, you just have the luxury to play with the "exposure" slider (in say, Lightroom 4.4) until you get the overall brightness you want from some "underexposed" raw file. What an embarassment, looking at all the unneeded bracketing exposures in my image database.

Obviously all this is a time/error-saver for raw users of a Nex C3 taking real photos in the field. Where they otherwise would have fiddled with their cam to get it over ISO 800, or waited while their camera clattered through bracketed exposures, or been held up from taking their next exposure, while waiting for all the unnecessary raw files to shuffle on out to the memory card.

And what a delight to know that, without bothering with bracketing, you have always preserved highlight detail, in case you want the HDR look from a single exposure:

Hmm, you've gone and done it now - the ISO3200 shot seems just as good as the 800 version! Did it require careful RAW noise reduction or other massaging? My whole line of questioning was that ultimate IQ should bebetter by "doing high ISO" (raising brightness, pushing shadows etc) in RAW! Ok, it may be easier to set and forget ISO800 in the field, but is the struggle with a dark screen image really worth it? Of course, if preserving important highlights, if a high ISO will blow them, but otherwise? I'm not so convinced any more!!

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Jack Hogan
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to EinsteinsGhost, Oct 4, 2013

EinsteinsGhost wrote:

For most part, yes. Actually, the C3 did a pretty good job at ISO 3200 for that particular image. I do note a slight change in color between ISO 3200 and ISO 800+push, visible in the lower left corner (carpet). The color looks a bit washed out in the latter. And if the rendering is closer in the first, then this case may be a good example where leaving ISO 3200 might be better...

Without knowing whether the alleged color change is due to the sensor or to LR turning on its high-ISO charm it's impossible to determine which ISO produces 'better' IQ.

Jack

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EinsteinsGhost
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Re: example of convenient 4-stop "push" acceptable to many
In reply to RussellInCincinnati, Oct 4, 2013

Russell,

These images are not a good candidate to see banding since you're not really lifting any shadows but it is still influencing patterns (most visible in darker areas, around nose, for example). If there is any point to pushing in post, it is to be had if DR is an issue. You're not gaining on noise. In fact, 12,800 appears to have a slight edge.

Here're a couple from NEX-3:

50mm, f/2, 1/320s, ISO 12,800

50mm, f/2, 1/320s, ISO 800, +4EV

Banding starts to show in the left side of the frame (and there is also more chroma noise on the dark patterns themselves, which is also due to banding). And that is without having to lift the shadows completely (which begins to show distinct lines). Here is the original ISO 800:

RussellInCincinnati wrote:

For example, I find a "four stop push" from ISO 800 to 12800, Nex C3 raw files acceptable. I particularly see not the slightest hint of banding.

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EinsteinsGhost
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to Jack Hogan, Oct 4, 2013

Jack Hogan wrote:

EinsteinsGhost wrote:

For most part, yes. Actually, the C3 did a pretty good job at ISO 3200 for that particular image. I do note a slight change in color between ISO 3200 and ISO 800+push, visible in the lower left corner (carpet). The color looks a bit washed out in the latter. And if the rendering is closer in the first, then this case may be a good example where leaving ISO 3200 might be better...

Without knowing whether the alleged color change is due to the sensor or to LR turning on its high-ISO charm it's impossible to determine which ISO produces 'better' IQ.

Jack

Well, let us then discuss EVERY possible combination, and find out the optimal solution, instead of a moving target.

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RussellInCincinnati
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a less dogged example, iso 12800 versus "pushed" 800
In reply to boardsy, Oct 4, 2013

Boardsy: Hmm, you've gone and done it now - the ISO3200 shot seems just as good as the 800 version! Did it require careful RAW noise reduction or other massaging?

Absolutely not. Both photos had all the same nearly-default Lightroom 4.4 processing (which purports to apply chrominance noise reduction +25 and no luminance noise reduction) except for moving the exposure slider to +1.75 EV or whatever for the "ISO800" photo.

Boardsy: My whole line of questioning was that ultimate IQ should bebetter by "doing high ISO" (raising brightness, pushing shadows etc) in RAW! Ok, it may be easier to set and forget ISO800 in the field, but is the struggle with a dark screen image really worth it? Of course, if preserving important highlights, if a high ISO will blow them, but otherwise? I'm not so convinced any more!!

Whether or not you personally can tolerate the dark screen is the main issue. There really is practically no image quality issue for ordinary work with Nex C3 raw files, see my rather typical portraiture-type examples below.

By my experimenting (which am not going to continue, because the differences between photos with ISO12800 vs 800 get down to nit-picking that nobody in my business cares about), it comes down to: in exchange for the hassle of the dark screen you get (a) guaranteed fabulous highlight detail (b) less field time fiddling with ISO and possibly (c) faster shot-to-shot time, less file-writing time and less file-transferring time, if you are the picky sort who normally brackets high-ISO photos.

By the way by putting on the C3 a tiny flash unit, or with any more fully-featured Nex 5x model, you can get to an always-bright screen mode no matter what the stored raw file brightness may be.

Above ISO 12800 on Nex C3. A few moments spent moving the "highlights" slider down, and fiddling with the "shadows" slider a bit, in the Lightroom 4.4 raw file.

Notice that even the models become happier when you leave the camera at ISO 800. 
Only difference between the workflow for photo and the one above was: (a) no need to change the highlights slider, (b) had to move the shadows slider down a bit, and (c) had to move the exposure slider to about +3.91 EV. Can't really say it took any longer in post-processing to produce the ISO 800 image than the "ISO 12800" image.

Boardsy, comparing in-camera ISO12800 to in-Lightroom ISO 800, am not seeing any Nex C3 difference worth writing home (or the forum) about.

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RussellInCincinnati
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nice example of Nex 3 noise differences. Also which one is which?
In reply to EinsteinsGhost, Oct 4, 2013

EinsteinsGhost wrote: Russell, These images are not a good candidate to see banding since you're not really lifting any shadows...In fact, 12,800 appears to have a slight edge...Here're a couple from NEX-3:

50mm, f/2, 1/320s, ISO 12,800

50mm, f/2, 1/320s, ISO 800, +4EV

Banding starts to show in the left side of the frame (and there is also more chroma noise on the dark patterns themselves, which is also due to banding). And that is without having to lift the shadows completely (which begins to show distinct lines).

Yes, the increased chroma noise is visible as you conveniently point out in this example of a photo with lots of featureless area. And it's excellent and useful to be aware of these differences.

As a dirt-ordinary practical matter, in for example typical Nex C3 portraiture, I don't see enough difference to be keep me from saving the trouble of moving an ISO control from 800 to 12800 in the field, or worrying about tiresome exposure bracketing to preserve highlight detail. Which one is which below, in-camera iso 800 or iso 12800?

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Jack Hogan
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to EinsteinsGhost, Oct 4, 2013

EinsteinsGhost wrote:

Jack Hogan wrote:

EinsteinsGhost wrote:

For most part, yes. Actually, the C3 did a pretty good job at ISO 3200 for that particular image. I do note a slight change in color between ISO 3200 and ISO 800+push, visible in the lower left corner (carpet). The color looks a bit washed out in the latter. And if the rendering is closer in the first, then this case may be a good example where leaving ISO 3200 might be better...

Without knowing whether the alleged color change is due to the sensor or to LR turning on its high-ISO charm it's impossible to determine which ISO produces 'better' IQ.

Jack

Well, let us then discuss EVERY possible combination, and find out the optimal solution, instead of a moving target.

I'd prefer to look at a couple of raws myself.

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EinsteinsGhost
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Re: no more low-light bracketing or high ISO setting, Nex C3 raw
In reply to Jack Hogan, Oct 4, 2013

Jack Hogan wrote:

EinsteinsGhost wrote:

Jack Hogan wrote:

EinsteinsGhost wrote:

For most part, yes. Actually, the C3 did a pretty good job at ISO 3200 for that particular image. I do note a slight change in color between ISO 3200 and ISO 800+push, visible in the lower left corner (carpet). The color looks a bit washed out in the latter. And if the rendering is closer in the first, then this case may be a good example where leaving ISO 3200 might be better...

Without knowing whether the alleged color change is due to the sensor or to LR turning on its high-ISO charm it's impossible to determine which ISO produces 'better' IQ.

Jack

Well, let us then discuss EVERY possible combination, and find out the optimal solution, instead of a moving target.

I'd prefer to look at a couple of raws myself.

And that is where my argument came from... looking at images. If you need RAWs, ask the person who posted them.

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